1. Field of the Invention
The present invention relates to the field of network communications. More particularly, the present invention relates to systems and methods for providing a remote switching engine to monitor and control network traffic, wherein appended word source address port mapping is utilized.
2. Related Art
Computer networks in business enterprises, such as a local area network (LAN), wide area network (WAN) or other Ethernet-based systems, facilitate communication among computer workstations. The pressure on these networks is steadily increasing. More and more users are demanding more information and faster speed from increasingly distributed locations. At the same time, demanding new applications and excessive Internet use are not only changing bandwidth requirements, they are also altering traditional traffic patterns.
When LAN networks were first introduced in the 1980's, a physical limit was quickly reached because of the LAN cable limitations. LAN bridges were introduced to solve this problem, tying these cables together to form larger networks. The bridge allowed the transparent passing of packets between LAN segments. Moreover, these bridges could also eavesdrop on the packets and learn which media access control (MAC) addresses were on each LAN segment. This allowed them to keep unicast traffic on the appropriate LAN segment. To utilize the bridges, MAC level broadcasts were required. Broadcasts not only used network bandwidth, but they also used processing power on every host system to which the broadcast was being passed. The processor on the host system had to analyze every broadcast packet up through the network layer to see if the packet was addressed to it. Eventually, MAC level broadcasts became an intolerably large percent of the network traffic. To solve this problem, routers were introduced to segment the network into separate domains.
At the router boundary, all broadcasts were intercepted and the router would decide which LANs on which the broadcast would be propagated. To achieve this, the router would look into level 3 headers and force a network to be segmented into network level broadcast domains. Although this solved the problem of excessive broadcasts within the network, it introduced an expensive device that would add latency, limit throughput and increase complexity of the network. To limit the throughput loss across a router, users were forced into topologies where servers and clients needed to remain within the same broadcast domain. Therefore, switches were then introduced to allow the creation of Virtual Local Area Networks (VLAN), allowing users to segment their networks without the high costs of routers or low port count of bridges. The first generation switches forwarded packets through the VLAN without examining the packet validity until after the packet had been forwarded. These switches did not prevent the occurrence of unnecessary and excessive traffic across the VLAN, which slowed down the network and required each end node and computer connected to the network to receive and analyze those packets. This led to the overall loss of network bandwidth. To solve this problem, second-generation switches were created.
The second generation switches implement broadcast isolation and level 3 network switching at the switch level through end-to-end learning sequences, or learning hits. The second-generation switch comprises a switching application specific integrated circuit (ASIC) and a central processing unit (CPU) connected to a plurality of ports. The switching ASIC has a database which enables it to look up addresses that it has previously obtained and to forward frames to the addresses. When frames are to be sent through a second-generation switch, or a number of them, the switch(es) has to become aware of the location of the sender and the receiver of the frames. That is, the switch(es) has to learn ports with which source addresses and destination addresses of the frames are associated and update the information into the database.
FIG. 1 shows normal control frame paths of a prior art system in which switching ASICs learn the ports where the sender and the receiver reside. Three stacked switches 10, 20, 30 are illustrated in FIG. 1. Each of these switches includes a local CPU and a switching ASIC. For example, the switch 10 includes a local CPU 12 and a switching ASIC 15. In a normal frame control path, such as control paths 13, 23, 33, frames received by the switch 10 with unknown addresses are sent to the local CPU 12 through a PCI bus for the required learning. This introduces the requirement of having a CPU in every platform containing a switch. Overheads, such as the PCI bus, memory, flash, etc. are also present. Together, they increase costs to a system having many of these platforms. In addition, with different local CPUs monitoring and managing network traffic separately, a single point of management is not achieved. Therefore, there is a need for a system and method to provide a system that eliminates the need for having a CPU in every platform while allowing a single logical platform that facilitates a single point of management.